The invention relates to a circuit arrangement for an interference data alarm system in communication facilities, particularly in telephone equipment, in which a maintenance control station is centrally arranged in one of the facilities, in which a receiver test unit accommodates all error and condition messages, which are determined and transmitted by transmitting test units of unmanned secondary stations.
In smaller communication facilities, for example in telephone exchanges, errors within the equipment are relatively rare. For this reason it is uneconomical to have a maintenance man continuously available in each of these facilities. This would be particularly uneconomical in small branch facilities, whose maintenance was taken over by a particular maintenance firm. In order to economically operate there, and to nevertheless be available in the respective facility in case of an interference, it is known to establish a central maintenance control station in which, in case of an error or an interference of a facility, corresponding alarms are transmitted. Depending upon the type of interference signaled, the central maintainence control station sends a maintenance man to the facility which is interfered with, who can be intentionally employed for the removal of this interference in accordance with his training status and experience.
From telecontrol engineering it is already generally known to transmit interference data, counter positions and condition messages to a central testing and control location and to also call up or poll said data intentionally, when required. Moreover, the central station also introduces control and switching processes and acknowledges their execution.
A transmission of such error and condition messages to a central station is only then possible, however, when the facility from which the message is to be transmitted is yet so operable that the interference message can be sent. If, for example, the transmitting test unit for the messages is connected to the exchange like a subscriber in order not to provide its own message lines for the relatively rare interferences, an interference in one of the facilities taking part in the connection to the central maintenance control station already prevents the transmission of the interference message so that the equipment appears error-free. Even a power failure, for example, due to a released safety fuse within the exchange equipment, prevents an error message.